Segments - Schedule of Adjusted EBITDA and Reconciling Items (Details) - USD ($) $ in Millions	1 Months Ended		2 Months Ended	3 Months Ended			5 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	May 17, 2023	Jun. 30, 2024	Mar. 31, 2024	Mar. 31, 2023	May 17, 2023	Jun. 30, 2024
Segment Reporting Information [Line Items]
Adjusted EBITDA		$ 93	$ 47	$ 100			$ 725	$ 418
Interest expense and other finance charges		(33)	(59)	(62)			(163)	(121)
Income tax benefit (expense)		(19)	(198)	(112)			(212)	(181)
Depreciation, amortization and accretion		(28)	(68)	(75)			(200)	(150)
Nuclear fuel amortization		(25)	(9)	(28)			(33)	(63)
Reorganization gain (loss), net		0	838	0			799	0
Unrealized (gain) loss on commodity derivative contracts		41	(94)	91			(63)	(44)
Nuclear decommissioning trust funds gain (loss), net		39	11	27			57	102
Stock-based compensation expense		(16)	0	(8)			0	(16)
Long-term incentive compensation expense		0	0	(6)			0	(16)
Gain (loss) on asset sales, net		0	15	561			50	885
Impairments		0	(16)	0			(381)	0
Operational and other restructuring activities		(12)	(9)	(19)			(17)	(21)
Development expenses		(2)	(3)	0			(10)	0
Non-cash inventory net realizable value, obsolescence, and other charges		(3)	(32)	(2)			(56)	(3)
Noncontrolling interest		8	9	7			14	18
Other items		2	(1)	(3)			(15)	11
Net Income (Loss)	$ 31	31	419	458	$ 319	$ 46	465	777
Corporate and Eliminations
Segment Reporting Information [Line Items]
Interest expense and other finance charges		(33)	(59)	(62)			(163)	(121)
Net Income (Loss)		(14)	(12)	(13)			(30)	(42)
PJM
Segment Reporting Information [Line Items]
Adjusted EBITDA		72	44	95			688	375
PJM | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA		72	44	95			688	375
Interest expense and other finance charges		0	0	0			0	0
Other
Segment Reporting Information [Line Items]
Adjusted EBITDA		21	3	5			37	43
Other | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA		21	3	5			37	43
Interest expense and other finance charges		$ 0	$ 0	$ 0			$ 0	$ 0